1. Field of the Invention
The present invention relates to a method of making a core of a magnetic thin film head suited for high-density magnetic recording.
2. Description of the Prior Art
A magnetic thin film core of a high-density magnetic recording thin film head for use in, for example, a hard disk drive is generally made up of magnetically soft layers. Because the direction of a magnetic path during operations of the head is determined, uniaxial magnetic anisotropy is generally induced in the magnetically soft layers so that an axis of easy magnetization may be directed so as to be perpendicular to the direction of the magnetic path. By doing so, an axis of hard magnetization is directed in parallel with the direction of the magnetic path, and hence, the magnetic core acts as a core having an initial permeability showing superior high-frequency characteristics.
In this case, the magnetic domain structure is generally such that 180.degree. magnetic domain walls are arrayed generally perpendicular to the direction of the magnetic path by inducing the uniaxial magnetic anisotropy in the magnetic core material. However, because the magnitude of the head output or that of noises greatly depends upon the stability of the magnetic domain structure within the core or the pattern of magnetic domains, how to control the magnetic domain structure within the magnetic core is especially important in laminating magnetic core films. Conventionally, a method of controlling magnetic domains of a magnetic thin film core made up of magnetically soft layers has been proposed wherein an even number of magnetically soft layers are laminated one upon another with a very thin non-magnetic insulating layer interposed between two adjoining magnetically soft layers, thereby causing each magnetic layer to have a single magnetic domain structure. This method provides a stable structure wherein two adjoining layers are magnetostatically coupled while they have respective directions of magnetization opposite to each other.
In applications where a multi-layer structure is composed of the magnetically soft layers together with the non-magnetic insulating layers, for example, in the manufacturing process of generally available magnetic thin film heads, the magnetically soft layers are generally made by a wet process such as, for example, electroplating. In such cases, it is difficult to laminate the non-magnetic insulating layers using the same wet process. Furthermore, a dry process wherein each lamination is carried out outside a plating bath is very complicated and has disadvantages in bonding properties between adjoining layers.